1. Field of the Invention
The present invention relates to a running surroundings recognizing apparatus and a running surroundings recognizing system which recognize information on the running surroundings of a self-vehicle using a running surroundings recognizing sensor mounted on the vehicle.
2. Description of the Related Art
As performance of a vehicle is improved, it becomes important to equip the vehicle with a preventive safety functions of recognizing the running surroundings such as a running lane, the other vehicles, detecting a possible status of occurrence of accident, and calling the driver""s attention for operation of avoiding a danger by sounding an alarm, or automatically controlling the vehicle to actively prevent the accident.
An important thing in order to realize the preventive safety functions is an apparatus for recognizing running surroundings using a sensor. In order to realize the running surroundings recognizing apparatus of such a kind, a camera, a laser radar, an extremely high frequency radar or the like have been commonly used.
In detail, a following distance alarm system, which measures a distance to a preceding vehicle running before a self-vehicle and sounds an alarm when the distance between the vehicles becomes smaller than a preset value, is becoming commercially available. Further, a system not only cautioning the driver, but positively controlling the vehicle, for example, an auto-cruise system, which controls running so as to keep the following distance constant, is becoming commercially available.
However, because the laser radar or the extremely high frequency radar (hereinafter, referred to as xe2x80x9cradarxe2x80x9d) used in these systems is required to measure a distance to a preceding vehicle 41 running far away ahead of a self-vehicle 40 with a limited electric power, there is a disadvantage in that width of the radar can not be widened and accordingly the sensing region 43 is narrow, as shown in FIG. 4. Therefore, when a vehicle is cutting in between the preceding vehicle 41 and the self-vehicle, the driver feels uneasy because the alarm does not sound or the control of constant following distance running does not work until the cutting-in vehicle comes very close to the self-vehicle. Further, when the cutting-in vehicle is sensed, the driver fees uncomfortable because the self-vehicle is suddenly decelerated, for example, during constant following distance running.
Sensing of a cutting-in vehicle is, therefore, a important problem, and a detection system for detecting a vehicle cutting in ahead of a self-vehicle is disclosed in Japanese Patent Application Laid-Open No.7-230600. In this apparatus, a cutting-in vehicle is detected as follows. An image within a range of vision 44 of a camera in front of the self-vehicle is imaged using the camera, and using the image a width of an object estimated to be a preceding vehicle 42 is detected from a traffic lane of the self-vehicle running and an outline of the image. A cutting-in width of the object estimated to be the preceding vehicle 42 into the traffic lane is obtained, and a degree of cutting-in is calculated based on the width of the object and the cutting-in width, and then alarm generation is switched to brake control depending on the magnitude of the degree of cutting-in.
If a distance to the cutting-in vehicle is estimated, the distance can be calculated through a coordinate transformation based on a position in the image.
However, the above conventional technology does not take it into consideration that the height of the vehicle is varied depending on number of passengers and accordingly the height of the camera mounted on the vehicle is changed. Further, since a mounting position of the camera is varied depending on a type and design of a vehicle, in most cases an actual mounting position of the camera does not agree with the design value and consequently fine adjustment (hereinafter, referred to as tuning) is always required. Nevertheless, the conventional technology is difficult to cope with the problem. This matter will be described in detail below.
Estimation of a distance to a cutting-in vehicle from an image imaged by a camera is performed as follows. Here, coordinate transformation between a coordinate system taking a lens of the camera as the origin (called as a world coordinate system) and a coordinate system set on the image plane (called as an image coordinate system).
These matters will be described below, according to the following order.
A. Definitions of the world coordinate system and the image coordinate system
B. Estimation of a distance of a cutting-in vehicle on the image coordinate system
A. Regarding definitions of the world coordinate system and the image coordinate system
 less than World coordinate system greater than 
As shown in FIG. 2, the world coordinate system X, Y, Z) is a coordinate system fixed on a vehicle and a right-hand coordinate system taking the heading direction of the vehicle from the center of the lens as Z-axis. Therefore, the origin (0, 0, 0) is the center of the lens.
 less than Image coordinate system greater than 
As shown in FIG. 2, x-axis of the image coordinate system (x, y) is parallel to and in the direction opposite to the X-axis of the world coordinate system, and y-axis is in the direction opposite to the Y-axis and vertically inclines to the optical axis of the lens of the imaging apparatus by an inclination angle (angle of depression) xc3x8.
Accordingly, letting the focal distance of the lens of the camera of the imaging apparatus be F. the origin of the image coordinate system becomes (0. F sin xc3x8, xe2x88x92F cos xc3x8) in the world coordinate system.
Relation between a point P (X, Y, Z) in the world coordinate system and a point q (x, y) in the image coordinate system which is the point P projected on the image can be expressed by the following Equation 1.
x=xe2x88x92FX/(Z cos xc3x8xe2x88x92Y sin xc3x8)
y=xe2x88x92F(Y cos xc3x8xe2x88x92Z sin xc3x8)/(Z cos xc3x8xe2x88x92Y sin xc3x8)xe2x80x83xe2x80x83(Equation 1)
B. Regarding estimation of a distance of a cutting-in vehicle on the image coordinate system
Letting a height from the road surface to the center of the lens of the camera be Yd, the coordinates of the cutting-in vehicle become the coordinates (X, xe2x88x92Yd, Z) in the world coordinate system because the cutting-in vehicle P is running on the road. Therefore, the coordinates of the cutting-in vehicle P can be expressed by the following Equation 2.
X=xe2x88x92(Z cos xc3x8xe2x88x92Yd sin xc3x8)/F
Z=(FYd cos xc3x8xe2x88x92yYd sin xc3x8)/(y cos xc3x8xe2x88x92F sin)xe2x80x83xe2x80x83(Equation 2)
Using Equation 2, the position of the cutting-in vehicle can be related with the position in the image.
It can be understood from Equation 2 that when the mounting position Yd of the camera is varied, the accuracy of the position of the cutting-in vehicle is largely affected.
Although the example of the running surrounding recognizing apparatus employing the camera as the imaging apparatus (sensor) is described here, the similar problem occurs whatever sensor for recognizing running surroundings, that is, a sensor other than a camera, for example, a radar is employed.
That is, the sensing region of the sensor is a region on the image coordinate system which is set corresponding to the sensor. By displacement in the mounting position of the sensor from the design value which may be caused at mounting it to the vehicle, or by lowering of the vehicle caused by load or number of passengers, or by change in the attitude of the vehicle caused a running condition, the mounting position or attitude of the sensor of the running surrounding recognizing apparatus is changed. The position of the detecting region on the image coordinate system is also changed corresponding to change in the mounting position or the attitude of the sensor.
In order to solve the above problem, an object of the present invention is to provide a running surrounding recognizing apparatus which is capable of accurately recognizing information in regard to running of a self-vehicle even if a mounting position of a sensor for running surrounding recognition is changed, and to provide a vehicle running control apparatus using the running surrounding recognizing apparatus.
In order to attain the above object, a running surrounding recognizing apparatus in accordance with the present invention is mounted on a vehicle and recognizes running surroundings of the vehicle using a sensor, and the running surrounding recognizing apparatus comprises a communication means for receiving data in regard to a mounting position of the sensor on the vehicle input from the external; a sensing region determining means for determining a sensing region which is sensed by the sensor based on the data received through the communication means; and a recognizing means for recognizing running surroundings from the sensing region determined by the sensing region determining means and a sensed result by the sensor.
Further, in order to attain the above object, a running surrounding recognizing apparatus in accordance with the present invention is mounted on a vehicle and recognizes running surroundings of the vehicle using a sensor, and the running surrounding recognizing apparatus comprises a receiving means for receiving data in regard to a sensing region of the sensor input from the external; and a recognizing means for recognizing running surroundings from the received sensing region and a sensed result by the sensor. Furthermore, a running surrounding recognizing system may be constructed using a plurality of such running surrounding recognizing apparatus.